1. Field of the Invention
The present invention relates to a pump unit that includes plurality of hydraulic pump bodies respectively fluidly connected to plurality of hydraulic motor bodies, which are disposed away from the pump unit, so as to form closed circuits.
2. Related Art
In a working vehicle, it is desirable to have a free space at a central portion in a width direction of the vehicle without enlarging the entire vehicle size. That is, by forming the free space at the central portion in the width direction of the vehicle, the free space can be used as an installation space for a mid-mount mower, used as a center discharger path and, further, used as an installation space for a mower lifting cylinder, thus enhancing the degree of freedom of design of the working vehicle.
For example, in U.S. Pat. Nos. 4,395,865 and 5,809,756 (hereinafter, referred to as cited references 1 and 2, respectively), there is proposed a working vehicle comprising a hydraulic pump unit operatively connected to a driving source, and a pair of hydraulic motor units allocated and arranged on both sides in a width direction of a vehicle so as to drive a pair of right and left driving axles, wherein the hydraulic pump unit and the pair of hydraulic motor units are fluidly connected to each other via conduits so as to form a pair of HST (hydrostatic transmission).
The conventional working vehicle having the above configuration is effective in preventing a traveling-system transmission mechanism to be interposed between the pair of driving axles, but is ineffective with regard to the following points.
That is, in the working vehicle including the pair of HST as its traveling-system hydraulic actuator, a working machine such as a mower device, and a working-machine-system hydraulic actuator such as a hydraulic lifting device for lifting up and down the working machine may be provided according to specification.
In the working machine including the HST and the working-machine-system hydraulic actuator, a traveling-system hydraulic pressure source for replenishing the HST, and a working-machine-system hydraulic pressure source for supplying operation fluid to the working-machine-system hydraulic actuator must be provided.
However, in the conventional working vehicle of the type in which the traveling-system hydraulic pressure source and the working-device-system hydraulic pressure source are provided, there have not been made proposal in view of effectively forming the hydraulic pressure sources.
The present invention has been made in view of the above conventional art, and it is an object of the present invention to provide a pump unit applicable to a working vehicle equipped with a working machine, wherein the pump unit includes plurality of hydraulic pump bodies respectively fluidly connected to plurality of hydraulic motor bodies, which are disposed away from the pump unit, so as to form closed circuits, and is capable of improving the efficiency in replenishing the closed circuits and supplying operation fluid to the working-machine-system hydraulic actuator.